Sealed condition inspection device

ABSTRACT

A sealed condition inspecting device comprising a support unit for supporting an element to be inspected for a sealed condition, a pair of electrodes in contact with the portion to be inspected of the element to be inspected and supported by the support unit, an electrical variable detecting unit for detecting an electrical variable in the portion to be inspected, and a sealed condition judging means for judging the acceptability of a sealed condition based on the electrical variable. In fact, since the acceptability of a sealed condition is judged based on an electrical variable in the portion to be inspected, whether or not a defective sealed condition has occurred can be determined independently of the subjectivity of the operator, whereby a sealed condition can be inspected for a sealed condition without unpacking them, not only inspection work can be simplified but reliability in the quality of an element to be inspected can be improved.

FIELD OF THE INVENTION

The present invention relates to the sealed condition inspection device.

BACKGROUND ART

The packaging container containing liquid food, such as milk and softdrinks, has been manufactured by using a web-like packaging material ora packaging container blank-like packaging material and sealing thepredetermined part of each packaging material with heat sealing orultrasonic sealing, etc. For instance, the packaging container wasformed by making the packaging material into a tube-like material,sealing the material in vertical direction using the vertical sealingdevice as the 1 st sealing device, sealing the material transversallyusing the transversal sealing device as the 2nd sealing device at thepredetermined length while filling liquid food into the material,cutting the material to form the original packaging container with thebrick-like shape, and then forming the original packaging containeragain to complete forming the packaging container.

The packaging material is sealed by pinching with the predeterminedpinching pressure and applying heat on the surface to melt the resin.However, poor sealing may occur when the melted resin escapes from thesealed part and sufficient amount of resin do not remain on the sealedpart according to the pinch pressure, sealing temperature, and resintype. With poor sealing, liquid food in the packaging container may leakor the quality of liquid food may deteriorate since air enters into thepackaging container.

Thus, an operator must select a sealed certain packaging container anddischarges liquid food from the packaging container, unpack thepackaging container, and inspect the sealed part of the packagingcontainer by viewing from the inside of the packaging container.

However, with the above-mentioned sealed condition inspection, thesealed condition cannot be judged properly since the judges varyaccording to the operator's subjectivity.

SUMMARY OF THE INVENTION

The object of the present invention is to provide the sealed conditioninspection device enabling accurate sealed condition inspection bysolving conventional problems of the sealed condition inspection method.To achieve the object, the sealed condition inspection device of thisinvention comprises a support unit for supporting an element to beinspected for a sealed condition, a pair of electrodes in contact withthe portion to be inspected and supported by the support unit, anelectrical variable detecting unit for detecting an electrical variablein the portion to be inspected, and a sealed condition device forjudging the sealed condition based on the electrical variable.

Another embodiment of the sealed condition inspection device of thisinvention discloses a support unit being established in a conveyor forconveying an element to be inspected.

Another embodiment of the sealed condition inspection device of thisinvention discloses a receiving plate as the support unit for mountingan element to be inspected.

Another embodiment of the sealed condition inspection device of thisinvention discloses at least one electrode being disposed movably andcan be located at the inspection position and the retreat position.

Another embodiment of the sealed condition inspection device of thisinvention discloses at least one electrode comprising a plurality ofelectrode elements.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an illustration of appearance of the first sealed conditioninspection device in the embodiment of this invention.

FIG. 2 is a conception diagram showing the feature of the filling upmachine in the embodiment of this invention.

FIG. 3 is the front view of an original packaging container in theembodiment this invention.

FIG. 4 is a perspective diagram of a packaging container of theembodiment of this invention.

FIG. 5 is a conception diagram of the sealed condition inspection deviceof the embodiment of this invention.

FIG. 6 is a conceptual diagram of the principle of the sealed conditioninspection method of the embodiment of this invention.

FIG. 7 is a block diagram of the sealed condition inspection device ofthe embodiment of this invention.

FIG. 8 is a waveform chart showing movement of the sealed conditioninspection device of the embodiment of this invention.

FIG. 9 is a figure showing the front panel of the control unit of theembodiment of this invention.

FIG. 10 is a figure showing electrode structure of the embodiment ofthis invention.

FIG. 11 is a figure showing other electrode structure of the embodimentof this invention.

FIG. 12 is front view of the second sealed condition inspection portionof the embodiment of this invention.

FIG. 13 is a side elevation of the second sealed condition inspectionportion of the embodiment of this invention.

PREFERRED EMBODIMENT OF THE INVENTION

Detailed description of the preferred embodiment of the presentinvention is explained with the accompanying drawings. Although thesealed condition inspection device used to detect the sealed conditionof the brick-shape packaging container is used for describing thisinvention, the description can be applied to the sealed condition ofother packaging containers.

FIG. 2 is a conception diagram showing the feature of the filling upmachine of the embodiment of this invention. FIG. 3 is the front view ofan original packaging container of this invention. FIG. 4 is aperspective diagram of a packaging container of the embodiment of thisinvention.

The packaging material having the web-shape, which is manufactured bythe not-illustrated packaging material making machine, is set to thenot-illustrated delivery machine, and then the material is conveyedusing the feeder.

The not-illustrated punch hole is provided on the packaging materialwhile the material is being conveyed and the not-illustrated inner tapeor pull-tab is attached to cover the punch hole. The packaging materialis conveyed in vertical direction with the not-illustrated forming ringsarranged on several positions in the direction that the packagingmaterial is conveyed. Then, the material is formed into thepackaging-material tube 11 and sealed using the vertical sealing deviceas the first sealing device. As shown in FIG. 3, the sealed portion S1is formed as the first sealed portion.

Then, liquid food is supplied to the packaging material tube 11 via thefilling tube. The packaging material tube 11 is pinched by the firstsealing jaw 44 and the second sealing jaw 45, that are components of thesecond sealing device, and the tube is sealed transversally at a certaininterval. Then, the tube is formed into the pillar shape to form theoriginal packaging container 18.

Both the first sealing jaw 44 and the second sealing jaw 45 have thecutting jaw 51 and heat sealing jaw 52. In this case, the packagingmaterial tube 11 is conveyed downwardly and the first sealing jaw 44 andthe second sealing jaw 45 having the same structure alternately work byshifting for ½ cycle of the process of the jaws in order to improve theprocessing speed of the filling machine.

The cutting jaw 51 has the cutting bar 53 (the right side of FIG. 2) onthe front end of the jaw, and the heat-sealing jaw 52 has the sealingblock (inductor insulator) 54, which has two indictors 55, on the frontend of the jaw. The transversally sealed portion S2, which is formed asthe second sealed portion and has two sealing lines, is formed byadvancing the cutting jaw 51 and the heat sealing jaw 52 is advanced,contacting the facing surfaces of the packaging tube 11 by pinching thetube using the cutting bar 52 and the sealing block 54.

The flat cutter knife 56 extending transversally is provided on thecenter of the cutting jaw 51 to freely move (moving in left and rightdirections in FIG. 2). The cutter knife 56 (moving in the rightdirection in FIG. 2) can cut the sealed portion between the two lines ofthe transversally sealed portion S2.

The cylinder 57 is provided on the rear end of the cutter knife (leftside of FIG. 2) and the cutter knife 56 advances/retreats byproviding/exhausting air to the cylinder.

The cutting jaw 51 and the heat sealing jaw 52 has a pair of the formingflaps 46 and 47 provided to freely swing and guide the packagingmaterial tube 11 by surrounding the tube.

The cutting jaw 51 and the heat sealing jaw 52 advance and both ends ofthe packaging material tube 11 contact when the first sealing jaw 44 isat the sealed portion cutting start position in FIG. 2. The firstsealing jaw 44 descends while pinching the packaging material tube 11and the transversally sealed portion S2 and the original packagingcontainer 18 are formed during the jaw descends.

The second sealing jaw 45 makes the cutter knife 56 advance in front ofthe sealed portion cutting end position and cut the portion between twosealing lines of the transversal sealed part S2 to separate the originalpackaging container 18 when the jaw is at the sealed part cutting endposition.

The cutting jaw 51 and the heat-sealing jaw 52 of the second sealing jaw45 retreat and move upwardly to the sealed portion cutting startposition after cutting the portion between two sealing lines of thetransversally sealed portion S2. The cutter knife 56 of the firstsealing jaw 44 advance to cut the portion between two sealing lines toremove the original packaging container 18 when the cutting jaw 51 andthe heat sealing jaw 52 advance from the sealed portion cutting startposition.

In addition, the not-illustrated cylinder mechanism is arranged on thefirst and the second sealing jaws 44 and 45, so that the cutting jaw 51and the heat-sealing jaw 52 pull each other at the sealed portioncutting start position and the pinching pressure becomes high, bysupplying, for example, compressed air into the cylinder mechanism.

The original packaging container 18 is formed into the predeterminedform in accordance with the formed fold and the packaging container isformed into the brick-type packaging container 10 containing thepredetermined amount of liquid food. The packaging container comprises afront wall 10 a, a rear wall. 10 b, side walls 10 c and 10 d, a topsurface wall 10 e and a base wall 10 f, an ear piece 10 g (one ear pieceis shown in FIG. 4) folded from 10 e to 10 c and 10 d sides and an earpiece folded from 10 c and 10 d to 10 f side.

In this case, the vertically sealed portion S1 is formed with the topsurface wall 10 e, the rear wall 10 b, and the base wall 10 f. Thetransversally sealed portion S2 is formed with the top surface wall 10 eand the ear piece 10 g on the top surface wall 10 e and the bottom wall10 f and the ear piece on the bottom wall 10 f.

The packaging material has a lamination structure in a direction fromoutside to inside when the packaging container is formed. The laminationstructure comprises a first resin layer formed as the inner resin layer,such as polyethylene, the aluminum foil layer used as the barrier layer,the paper base, and a second resin layer, such as polyethylene, used asthe outer layer. The resin layer (e.g., polyester) can be used as thebarrier layer instead of the aluminum foil layer. In addition, 38 is theguiding roller guiding the packaging material tube 11.

The packaging material is sealed by attaching the resin layers of thefirst layer by pinching the material with the predetermined pinchingpressure using the cutting jaw 51 and the heat sealing jaw 52 andapplying heat on the surface of the material to melt the resin orswinging the material with supersonic wave. The poor sealing may occurwhen the melted resin escapes from the transversally sealed portion S2and sufficient amount of resin do not remain on S2 according to thepinching pressure, sealing temperature, and resin type. With poorsealing, liquid food in the packaging container 10 may leak or thequality of liquid food may deteriorate since air enters into thepackaging container 10.

Thus, the sealed condition inspection device is disposed to inspect thesealed condition. The sealed condition inspection device has two modes,i.e., automatic mode and manual mode. The packaging container 10, whichis extracted from the filling machine, is delivered to the first sealedcondition inspection part and the transversally sealed portion S2 isautomatically inspected in automatic mode.

FIG. 1 is an illustration of appearance of the first sealed conditioninspection device in the embodiment of this invention. FIG. 5 is aconception diagram of the sealed condition inspection device of theembodiment of this invention. FIG. 6 is a conceptual diagram of theprinciple of the sealed condition inspection method of the embodiment ofthis invention. FIG. 7 is a block diagram of the sealed conditioninspection device of the embodiment of this invention. FIG. 8 is a waveform chart showing movement of the sealed condition inspection device ofthe embodiment of this invention.

In the drawing, 71 is the control unit, 72 is the conveyor disposed onthe back of the control unit 71, and 73 is the conveyor conveying theelement to be inspected, which is formed by the insulating material, andoperating with the not-illustrated conveyor motor. The first sealedcondition inspection part is disposed on the predetermined positions onthe conveyor 73 and the conveyor 73 works as the support unit for thepackaging container 10. The control unit 71 is disposed on the firstsealed condition inspection part. In addition, the guides G1 and G2,that are formed with the insulating material, are disposed on the frontside and the rear side of the device along with the lines of theconveyor 73 in the first sealed condition inspection part and the guideshold the packaging container 10.

In the first sealed condition inspection part, a pair of the first andthe second electrode parts (75, 76) are disposed on the not-illustratedsupporting holder located on the upper part of the packaging container10. The electrode parts advance/retreat in A and B directions in FIG. 1by driving the not-illustrated the first and the second driving partscomprising air cylinder and so on. The electrode parts move to theinspection position when the parts advance. On the other hand, theelectrode parts move to the retreat position when the parts retreat. Theelectrodes 21, 22 are disposed on the tip of the electrode parts 75 and76, respectively.

Although the original packaging container 18 is formed into thepackaging container 10 by forming along the predetermined fold, the earpiece 10 g is attached on the side walls 10 c and 10 d after thetransversally sealed part S2 is tilted to the front wall 10 a side ifthe transversally sealed portion S2 has one of the form shown in FIG. 1or FIG. 4. The top surface wall 10 e has the vertical sealed portion S2tilted to the front wall 10 a side.

Thus, the packaging container 10 is set on the conveyor 71 in the waythat the front wall 10 a of the packaging container to be appeared whenconveying the packaging container to the first sealed conditioninspection part. When the packaging container 10 reaches the firstsealed condition inspection part, the vertically sealed portion S2 movesup from the top surface wall 10 e and the portion is slightly tiltedtoward the top surface wall.

Therefore, the shape of the second electrode 22 is similar to wedge andthe electrode is formed by tilting the inspection surface 77 toward thetop surface of the device. In addition, the electrode part 75advances/retreats perpendicular to the inspection surface 77.

Therefore, the second electrode 22 is inserted into the lower part ofthe transversally sealed portion S2, which is slightly tilted to the topsurface wall, to attach the electrode to the part, and the firstelectrode 21 is abutted to the upper part of the transversally sealedportion S2 when both of electrode parts 75 and 76 are at the inspectionposition.

The sealed condition inspection device has two operation modes, i.e.,automatic code and manual mode. The packaging container 10 is stopped bythe not-illustrated stopper when the packaging container reaches thefirst sealed condition inspection portion and the motor conveying thepackaging container also slops.

When the electrode parts 75 and 76 advance to the inspection portion,the first electrode portion 75 presses the first electrode 21 to thetransversally sealed portion S2. When the inspection finishes, theelectrode parts 75 and 76 retreat to the retreat position. The motor forconveying the packaging container is activated again and the packagingcontainer 10 is conveyed with the conveyor 73. In this case, thepackaging container 10 having poor sealed condition is automaticallyextracted from the line with the judging device disposed below the firstsealed condition inspection portion.

The following part describes the operation of the sealed conditioninspection device.

In FIG. 5, S2 is the transversally sealed portion, 17 is the packagingmaterial comprising the first resin layer 12, the aluminum foil layer13, the paper matrix 14, and the second resin layer 15. When thepackaging material tube 11 (FIG. 2) is sealed transversally, the cuttingjaw 51 and the heat sealing jaw 52 advance and the packaging materialtube 11 is pinched or oscillated with the supersonic wave. In this case,both the first resin layers 12 contact and the resin on the layers, suchas polyethylene, are welded, so that the welding portion 16 is formed.

Two packaging materials 17 are bonded at the welding portion 16 in thetransversally sealed portion S2 and the portion has the function ofcondenser 31 since each of the first and the second resin layers 12, 15etc. comprise dielectric materials. If the resin, such as polyester, isused for the barrier layer, the barrier layer also comprises dielectricmaterials. In addition, the adhesive layer comprises the not-illustratedglue between the aluminum foil layer 13 and the paper matrix 14. Theadhesive layer also consists of dielectric materials.

The alternating current is supplied to the element F to be inspected,which is used to inspect the transversally sealed portion S2. With thecapacitance and the loss factor of the element F to be inspected, thesealed condition inspection device inspects the sealed condition.

Therefore, the sealed condition inspection device comprises a pair ofthe first and the second electrode parts 75 and 76, the power-supplyunit (AC) 23 generating the alternating current applied to the element Fto be inspected, the current sensor 24 detecting the capacitance and theloss factor of the element F to be inspected, the detection processingpart 25 reading the voltage generated by the power-supply unit 23 andthe current detected by the current sensor 24, the control part 26having the CPU controlling the sealed condition inspection device, thefirst display unit 27 having a display, the operation portion 28, andthe recording unit 29 recording the predetermined data etc. In addition,the current sensor 24 detects the alternating current flowing in theelement F to be inspected. The power-supply unit 23 detects thegenerated alternating current and the not-illustrated voltage sensor candetect the alternating voltage as electric variables.

When the first and the second electrodes 21 and 22 having conductivematerials are arranged facingly. When the sealed condition of thematerial to be inspected has the predetermined area, the element F to beinspected is pinched and pressed with the predetermined pressure. Theelectrodes 21 and 22 are connected through the power-supply unit 23 andthe current sensor 24 and the voltage generated by the power-supply unit23 is applied to the element F to be inspected.

The voltage applied to the element F to be inspected is set in responseto the property of the packaging material 17, such as each material orthickness of the first resin layer 12, the aluminum foil layer 13, thepaper matrix 14, and the second resin layer 15. When the voltage isapplied to the element F to be inspected, the equivalent circuit asshown in FIG. 6 is formed with the power-supply unit 23 and the elementF to be inspected. In this case, the element F to be inspected has theparallel circuit wherein the condenser 31 having the capacitance of Cpis arranged in parallel with the internal resistance 32 having theresistance of Rp. When the condenser 31 and the internal circuit 32 areconnected in the equivalent circuit, whether they are connected inseries or parallel is decided in accordance with the impedance of thecondenser 31 and the internal resistance 32. If the impedance of theinternal resistance 32 is extremely larger than that of the condenser 31like the transversally sealed portion S2, the internal resistance andthe condenser are connected in parallel.

When the area of the electrodes 21 and 22 is set as “s”, the thicknessof the element F to be inspected, that is, the distance between thedistance of the load electrodes (distance between the first electrodeand the second electrode), is set as “d”, and the dielectric constant isset as “ε”, the capacitance is obtained byCp=εS/d.

In this case, the amount of the capacitance Cp changes in the element Fto be inspected changes since the dielectric constant ε changesaccording to changes of the property of the packaging material 17, suchas the material or the thickness of the first resin layer 12, thealuminum foil layer 13, the paper matrix 14, and the resin layer 15. Theamount of the capacitance Cp significantly changes in the element F tobe inspected and the dielectric constant ε in the element F to beinspected significantly changes when the property of the layers made ofdielectric materials, such as the material or the thickness of the firstresin layers 12 and 15, the aluminum foil layer 13, and the paper matrix14 change.

In addition, the capacitance Cp of the material to be inspected changesaccording to the distance between load electrodes since the distancechanges according to the change of the sealing condition for thetransversally sealed portion S2, such as the melting temperature of theresin and the pinching pressure with the cutting jaw 51 and the heatsealing jaw 52. Higher melting temperature or the pinching pressure,larger amount of the melted resin escapes to both sides of thetransversally sealed portion S2, so that the thickness of the weldingportion 16 becomes thinner. Therefore, the distance between the loadelectrodes d become shorter and the amount of the capacitance Cpincreases.

When sealing the transversally sealed portion S2, the capacitance Cp inthe element F to be inspected changes according to the melting degree ofthe welding portion 16. When resin layers 12 are melted and thepackaging material 17 are attached, the amount of the resin in thetransversally sealed portion S2 decreases and the distance between theload electrodes d become shorter, so that the capacitance Cp of thematerial F to be inspected increases. When the first resin layer 12 maynot be melted even if the resin layers look melted, little weldingportion 16 is formed. Since the first resin layers 12 are attachedtogether, the amount of the resin on the transversally sealed portion S2does not decrease. Therefore, the distance D between the load electrodesand the capacitance Cp also do not change.

When the length of the sealing line used for transversally sealing thedevice changes, the area that the first and the second electrodes 21 and22 contact and the area S of the electrodes 21 and 22 change, so thatthe capacitance Cp of the element F to be inspected changes. The form ofthe first and the second electrodes is set not to project outwardly fromthe transversally sealed portion S2. It is preferable to set the widthof the first and the second electrodes 21, 22 as W and the length of theelectrodes as 2W when the sealing width of the transversally sealedportion S2 is set as W. When the electrodes 21, 22 project outwardlyfrom the transversally sealed portion S2, the condition of the meltedresin in the inside of the transversally sealed portion S2 is differentfrom the outside of the portion, so that the accuracy of the sealedcondition inspection become low.

The capacitance Cp can be used as the judging element of the sealedcondition since the capacitance Cp of the element F to be inspectedchanges according to the property of the packaging material 17, thesealing condition for the transversally sealing device, the sealingmethod, and the structure of the device and so on.

Therefore, the voltage Vs generated by the power-supply unit 23 is setaccording to the property of the packaging material 17, the sealingcondition for the transversally sealing device, the sealing method, andthe structure of the device and so on.

The impedance Zc of the condenser 31 can be obtained byZc=1/(2π·f·Cp)  (1)when the voltage Vs of the frequency F is applied to the element F to beinspected using the power-supply unit 23, and the current flowing thecondenser 31 is set as Icp and the current flowing the internalresistance 32 is set as Irp. In this case, the current Icp can beobtained byIcp=Vs/Zc=2·f·Cp·Vs  (2)and the capacitance can be obtained byCp=Icp/(2π·f·Vs)  (3).In addition, the voltage Vs is applied to the element to be inspected,the current Icp is applied to the first element to be inspected, and thecurrent Irp is applied to the second element to be inspected.

When the loss factor in the element F to be inspected is set as D, theloss factor can be obtained byD=1/(2π·f·Cp.Rp)  (4)and the resistance Rp of the internal resistance 32 can be obtained byRp=1/(2π·f.Cp·D)  (5)

Since current Irp flowing into the internal resistance 32 isIrp=Vs/Rp  (6),the current can be obtained by substituting the formula (6) in theformula (5):Irp=(2π·f·Cp·D).Vs  (7).

In addition, the formula will be Irp=Icp·D when the formula (3) issubstituted in the formula (7), so that the loss factor can be obtainedbyD=Irp/Icp  (8).

Therefore, the loss factor can be obtained with the ratio of the currentIrp to the current Icp, so that the loss factor can be used for judgingthe sealed condition.

The current It showing the electrical variable in the element F to beinspected can be obtained byIt=Icp+Irp  (9).

Since the capacitance can be obtained with the formula (3) and the lossfactor can be obtained with the formula (8), the capacitance Cp and theloss factor D can be calculated when the voltage Vs and the current Icpand Irp are obtained.

In this case, the value of the condenser 31 is the same as the value ofthe internal resistance 32 in the element F to be inspected, so that itis impossible to detect the value of the condenser and the internalresistance at outside of the element F to be inspected.

Therefore, the current Icp and Irp can be calculated based on thecurrent It detected using the current sensor 24. The current Irp has thesame phase as the voltage Vs applied to the element F to be inspected asshown in FIG. 8 since the current is applied to the internal resistance32. On the other hand, the phase of the current Icp is shifted for 90[°] from the voltage Vs since the current Icp is applied to thecondenser 31. Therefore, the current It (the voltage Vt generated byconverting the current It to the voltage Vt) is applied to the phaseseparation circuit to separate the current Icp and the current Irp.

The detection processing part 25 comprises the A/D converter 61 readingthe voltage Vs generated by the power-supply unit 23 and performing theanalog/digital conversion, the current/voltage convert part 62converting the current It to the voltage Vt after reading the currentIt, the same phase detection part 33 detecting the same phase as thevoltage Vs in the voltage Vt, the phase difference detection part 34detecting the phase difference of the voltage Vs, the A/D converter 35performing the analog/digital conversion after reading the same phasedetected using the same phase detection part 33, and the A/D converter36 performing the analog/digital conversion after reading the differentphase detected using the phase difference detection part 34. The phaseseparation part has the phase separation circuit comprising the samephase detection part 33 and the phase difference detection part 34.

The A/D converter 61 outputs the voltage Vs comprising digital signals,the A/D converter 35 outputs the current Irp comprising digital signaland the A/D converter 36 outputs the current Icp comprising digitalsignals. The output voltage Vs and the current Icp and Irp aretransmitted to the control unit 26. In addition, the applied voltagedetection part comprises A/D converter 61, the first current detectionpart for the material to be inspected comprises the phase differencedetection part 34 and the A/D converter 36, and the second currentdetection part for the material to be inspected comprises the same phasedetection part 33 and the A/D converter 35.

The control unit 26 reads frequency f, voltage Vs and current Icp andIrp set in the power-supply unit 23 and the not-illustrated capacitancecalculation processing mean calculates the capacitance Cp with theformula (3). The control unit 26 of the not-illustrated loss factorcalculation processing means performs the loss factor calculation tocalculate the loss factor D with the formula (8).

The recording unit 29 records the standard capacitance Cpref and thestandard loss factor Dref obtained by considering the type of thepackaging material 17, the sealing condition for the transversallysealing device, the sealing method, and the structure of the device andso on.

The not-illustrated first sealed condition judging device in the controlpart 26 performs the first sealed condition judging process and comparesthe calculated capacitance Cp with the standard Cpref by referring tothe table, then judges whether the deviationΔCp=ICp−Cpreflis less than the threshold Cpth or not.

When the deviation Δ Cp is less than the deviation Cpth, the sealedcondition is judged as good. On the other hand, the sealed condition isjudged as bad when the deviation Δ Cp is less than the threshold Cpth.The sealed condition can be judged using the first sealed conditionjudging device.

The not-illustrated second sealed condition judging device in thecontrol part 26 performs the second sealed condition judging process andcompares the calculated loss factor D with the standard Dref byreferring to the table, then judges whether the deviationΔD=ID−Dreflis less than the threshold Dth or not. When the deviation Δ D is lessthan the deviation Dth, the sealed condition is judged as good. On theother hand, the sealed condition is judged as bad when the deviation Δ Dis less than the threshold Dth.

The sealed condition can also be judged using the second sealedcondition judging device.

In this embodiment, the sealed condition is judged with the firstjudging processing or the second judging process. However, it ispossible to judge the sealed condition using both of the sealedcondition judging processes.

The following part describes the control unit 71.

FIG. 9 is a figure showing the front panel of the control unit of theembodiment of this invention.

In FIG. 9, 71 is the control unit, 27 is the display unit, 28 is thecontrol unit, Sw1 is the main switch used for switching on/off thecontrol unit, Sw2 is the mode switch used for switching auto mode andmanual mode, Sw3 is the switch used for switching on/off the first andthe second electrodes 21 and 22, SW4 is the switch for selecting aplural of electrode elements constituting the first and the secondelectrodes 21 and 22, t1 is the junction terminal connecting the controlunit 26 and the control unit 71, t2-t5 are junction terminals connectingelectrodes 21 and 22 (FIG. 1) and the control unit 71, 78 is the timer,81-84 are LED lamps, VM1 is the first setting volume of the voltage Vsgenerated by the power-supply unit 23 (ex. 8 [V]), VM2 is the secondsetting volume of the frequency F (ex. above 100 [kHz]) of thepower-supply unit 23, and VM3 is the third setting volume used forsetting the threshold of the capacitance Cp having Δ Cp of the deviationand the threshold Dth of the loss factor having Δ D of the deviation. Inthis case, the number of the Cpth and Dth can be set in the range of0-10. The LED indication lamps 81-84 illuminate to warn the operator.

The following part describes the first electrode 21 and the secondelectrode 22.

FIG. 10 is a figure showing electrode structure of the embodiment ofthis invention.

In FIGS. 10, 21 and 22 are the first and the second electrodes arrangedacross the element F to be inspected. In this case, the first and thesecond electrodes 21 and 22 have multiple electrodes structurecomprising multiple channels and multiple electrode elements Ei (1, 2, .. . , n). Therefore, one electrode element can be selected fromelectrodes 21 and 22 by using the switch SW4 (FIG. 9), so that it ispossible to inspect the sealed condition of the predetermined part ofthe element F to be inspected only.

FIG. 11 is a figure showing other electrode structure of the embodimentof this invention.

In FIGS. 11, 21 and 22 are the first and the second electrodes arrangedacross the element F to be inspected. In this case, the first electrode21 has multiple electrodes structure comprising multiple channels andmultiple electrode elements Ei, and the second electrode 22 has thesingle electrode structure comprising one electrode element. Therefore,one electrode element can be selected from electrode elements Ei of thefirst electrode 21 and the second electrode 22 by using the switch SW4(FIG. 9), so that it is possible to inspect the sealed condition of thepredetermined part of the element F to be inspected only. When poorsealing occurs in several points, the electrode structure shown in FIG.11 is preferred since it is impossible to specify the positions. In thiscase, the cost of the sealed condition device can be reduced. Thestructure of the electrodes 21 and 22 shown in FIG. 10 is preferred whenaccurate inspection is required. On the other hand, the structure of theelectrodes 21 and 22 shown in FIG. 11 is preferred when high accuracy isnot required, such as the case that the position having poor sealing isalready inspected, etc.

The following section describes the second sealed condition inspectionpart used to inspect the sealed condition in manual mode.

FIG. 12 is front view of the second sealed condition inspection portionof the embodiment of this invention.

FIG. 13 is a side elevation of the second sealed condition inspectionportion of the embodiment of this invention.

In the figures, 101 is the frame, 102 is the bracket, 103 is thesupporting holder, wherein the first electrode part 175 is disposed onthe supporting holder 103 and the second electrode part 176 is disposedon the frame 101 facingly with the first electrode part 175. The firstelectrode part 175 advances/retreats in the C mark indicated by thearrow mark by driving the driving part 104 comprising the air cylinder,etc. The part advances to the inspection position (moves downward inFIG. 11) and retreats to the retreat position (moves upward in FIG. 11).The first electrode 21 and the second electrode 22 are disposed on thetip of the first electrode part 175 and the second electrode part 176,respectively. In addition, 105 is the insulator used to insulate thesecond electrode 21 and 106 and 107 are insulators insulating the secondelectrode 22.

The conductive material is mounted on the second electrode 22 and thereceiving board 111 working as the supporting part of the material to beinspected and supporting the packaging container 10 is disposed. Theoperator can mount the original packaging container 18 (FIG. 2) on thereceiving board 111 and locate the first electrode part 175 on theinspection point, and then press the first electrode 21 to thevertically sealed portion S1 or the transversally sealed portion S2 tomake the electrode contact with any one of the sealed portions. In thiscase, the packaging container 10 itself works as the condenser.

In addition, the operator can inspect the sealed condition by extractingliquid food from the original packaging container 18 and putting theempty original packaging container 18 on the receiving board 111.

Therefore, with this invention, the sealed condition is inspected withthe current It flowing in the element F to be inspected when the voltageVs is applied to the material, not by the operator's subjectivity.Therefore, the sealed condition can be accurately inspected.

In addition, it is possible to simplify the inspection process since thesealed condition of the transversally sealed portion S1 and thetransversally sealed portion S2 can be inspected without opening thepackaging container 10. The reliability for the quality of the packagingcontainer 10 also improves with this process.

Various changes or modifications for this invention may be made withoutdeparting from the spirit and scope thereof, it is to be understood thatthe invention is not limited to the above-mentioned embodiments.

The sealed condition inspection device of this invention comprises asupport unit for supporting an element to be inspected for a sealedcondition, a pair of electrodes in contact with the portion to beinspected and supported by the support unit, an electrical variabledetecting unit for detecting an electrical variable in the portion to beinspected, and a sealed condition device for judging the sealedcondition based on the electrical variable.

With this invention, the sealed condition is inspected in accordancewith the electronic variable in the element to be inspected, not by theoperator's subjectivity. Therefore, the sealed condition can beaccurately inspected.

In addition, it is possible to simplify the inspection process since thesealed condition of the material to be inspected can be inspectedwithout opening the material. The reliability for the quality of thematerial to be inspected also improves with this process.

INDUSTRIAL APPLICABILITY

The sealing device of this invention can be utilized for the sealedcondition inspection device of the packaging container containing liquidfood, such as milk and soft drinks.

1. A sealed condition inspection device comprising (a) a support unitfor supporting an element to be inspected for the sealed condition, (b)a pair of electrodes in contact with the portion to be inspected andsupported by the support unit, (c) an electrical variable detecting unitfor detecting an electrical variable in the portion to be inspected, and(d) a sealed condition device for judging the sealed condition based onthe electrical variable.
 2. The sealed condition inspection deviceaccording to claim 1, wherein said support unit of the element to beinspected is established in a conveyor for conveying the element to beinspected.
 3. The sealed condition inspection device according to claim1, wherein said support unit is a receiving board for receiving theelement to be inspected to mount the element.
 4. The sealed conditioninspection device according to claim 1, wherein at least one of the pairof the said electrodes is movably disposed and can be located at aninspection position and a retreat position.
 5. The sealed conditioninspection device according to claim 1, wherein at least one of the pairof the said electrodes consists of a plurality of electrode elements.